With recent development of the semiconductor technology, the data transfer between LSIs has become to be performed by high-speed serial transmission. As an interface for converting transmit parallel data to serial data, outputting the serial data over a transmission line, and converting received serial data into parallel data, a circuit termed SERDES (SERializer and DESerializer) has come into wide spread use. This SERDES circuit will now be described with reference to FIG. 1. The SERDES includes a PLL (Phase Locked Loop) circuit 10 for generating an internal clock signal, a transmit circuit 11, and a receive circuit 12, as shown in FIG. 1.
The transmit circuit 11 includes a parallel-to-serial converting circuit 13 for serializing parallel data. The receive circuit 12 includes a clock and data recovery circuit 14 for extracting a clock synchronized with the received serial data from the data and for outputting the extracted clock signal (recovery clock) and the data, and a serial-to-parallel converting circuit 15 for converting the data into parallel data.
FIG. 19 shows an illustrative configuration of a clock and data recovery circuit described in Patent Document 1 of the present Assignee. Referring to FIG. 19, this clock and data recovery circuit includes a phase detector 201, integrators 202 and 203, a pattern generator 204, a mixer 205 and a phase interpolator 206. The phase detector 201 detects the phase relationship between input data and an extracted clock. A block made up of the integrators 202 and 203, pattern generator 204 and the mixer 205 generates a phase control signal for the phase interpolator. The phase interpolator 206 generates the extracted clock. The above-described loop takes charge of recovery of the clock and the data. As for the configuration of the clock and data recovery circuit, reference is made to, for example, the disclosure of Patent Document 2.
[Patent Document 1]
Japanese Patent Kokai Publication No. JP-P2005-5999A
[Patent Document 2]
Japanese Patent Kokai Publication No. JP-P2002-190724A